This invention relates to improvements in coal burning stoves intended for use in space heating applications. Although coal stoves have not been in wide use for many decades, recent difficulties in supply and costs of other fuels, such as oil and gas, has caused a renewed interest in space heating stoves. The present invention relates to improvements in coal-burning stoves which are intended to overcome a number of problems and disadvantages encountered with prior coal burning stoves. For example, one of the objectionable features of coal-burning stoves is that they tend to generate unpleasant fumes and gases particularly when starting a fresh fire or when adding coal to an already existing fire. It is believed that these fumes are the result of incomplete combustion which typically occurs before the fire has become hot enough to cause complete combustion. Typically, the noxious gases will be generated for fiteen to twenty minutes, during which time they may permeate the living space in which the stove is contained.
Another difficulty presented with prior coal stoves is that they often do not burn coals completely. Frequently, nuggets or "klinkers" are left with the ashes, indicating incomplete combustion and wasted fuel. It is believed that this is in large measure the result of the design of the grate and fire pot of the stove as well as the manner in which it is mounted within the stove and the geometric relationship between these internal elements of the stove. Also among the features of prior coal stoves which are believed to have presented difficulties is that the grates were moveably mounted so that they could be shaken to permit ashes to fall through the holes in the grates. While this was intended to provide for better air flow through the coals, it is believed that it would cause klinkers to become stuck in the grates which would tend to block the grates and impede proper air flow through the coals rather than assist it. It is among the general objects of the present invention to provide an improved coal stove which minimizes the foregoing and other difficulties encountered with prior coal stoves.
In brief, my stove includes a generally cylindrical body which may be formed from steel. An integral, one-piece fire pot which receives the coal has grate openings formed in its bottom wall. The pot is suspended at the lower region of the stove by a ring-like support secured to the inner periphery of the stove body. The pot is suspended from its upper circumferential lip and cooperates with the supporting ring to separate the interior of the stove into an upper chamber and a lower chamber. The fire pot projects downwardly into the lower chamber and its sidewalls are spaced from the surrounding stove wall to define an annular region at the upper portion of the lower chamber. The bottom wall of the fire pot is provided with a plurality of apertures to define a grate and to permit air to flow into the fire pot upwardly, through its bottom. The sidewalls of the fire pot, which cooperate to define the annular space, are imperforate. During normal combustion, air will enter the lower chamber through an appropriate door in the stove and will flow upwardly through the grate to continually furnish oxygen to the coals and to assure that the coals will burn properly, from the bottom up.
In order to better control the start of combustion and to assure complete combustion at the end of the load of coals, the pot supporting ring is provided with a plurality of apertures which surround the periphery of the pot and can be controlled to vary the cross-sectional flow area of the apertures, thereby enabling a controlled volume of air to flow directly from the lower chamber to the upper chamber, peripherally about and bypassing the fire pot. As will be described in further detail, the fire pot and bypass apertures are constructed and arranged so that they may be operated in a manner which overcomes the above-noted and other difficulties inherent in prior coal stoves.
It is among the general objects of the invention to provide an improved coal burning stove adapted for use in space heating applications.
A further object of the invention is to provide a coal-burning stove in which air can be circulated rapidly through the stove to continually and rapidly purge interior of the stove and minimize chance of noxious fumes leaking into the room.
Another object of the invention is to provide a coal-burning stove having an improved fire pot and grate construction and means for supporting the fire pot and grate which enhances complete combustion.
A further object of the invention is to provide a steel-bodied, coal-burning stove which does not require the use of insulating refractory materials along the interior of the stove.
Another object of the invention is to provide a coal-burning stove of generally higher efficiency yet which is of simplified and economical construction.